Bulbophyllum Thouars (1822: 3) is one of the largest orchid genera, including more than 1900 species widely distributed from tropical America, Africa, Madagascar, and mainland Asia to Australasia (Lindley 1830, Pearce & Cribb 2002, Seidenfaden 1979, 1992, Chen et al. 2009, Pridgeon et al. 2014). The species possess a wide range of vegetative form and floral structure (Bose et al. 1980). There are about 103 species (33 endemic) in 18 sections in China (Chen et al. 2009).

Section Stachysanthes (Blume ) Averynov (1994: 276) is distinguished by inconspicuous pseudobulbs and includes 72 species. There are five species (three endemic) of section Stachysanthes in China (Tsi 1999, Chen et al., 2009). During our fieldwork in Mengla County of Xishuangbanna, southeastern Yunnan, a new species of Bulbophyllum of sect. Stachysanthes was found in the limestone forest and described below.

Diagnosis: Bulbophyllum mengyuanense is similar to B. drymoglossum and B. hainanense, but can be distinguished from them by having yellow flowers with purple stripes, lateral sepals connate in their basal third, conspicuous column stelids and a labellum without a callus.